Writing instrument



FIG. 1 is a left side elevation view of a writing instrument showing my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a right side elevation view thereof;

FIG. 4 is a back elevation view thereof;

FIG. 5 is a top plan view thereof shown on an enlarged scale; and,

FIG. 6 is a bottom plan view thereof shown on an enlarged scale. 

CLAIM The ornamental design for a writing instrument, as shown and described. 